The present invention relates to mechanical heart valve prostheses. More specifically, the invention relates to a mechanism for attaching and implanting heart valve prostheses.
Implantable prosthetic heart valves are used for replacement of defective valves in hearts of patients. There are two general types of hearts valves, mechanical and bioprosthetic. One method of implanting a valve employs a sewing ring or suture cuff which is attached to and extends around the outer circumference of the valve orifice. The sewing cuff is made of a biocompatible fabric suitable for allowing a needle and suture to pass therethrough. The valve is typically sutured to a tissue annulus after the surgeon removes the native valve from the patient""s heart. The sutures are tied snugly, thereby securing the valve to the heart.
Attaching the suture cuff to the tissue annulus is time consuming, and requires a patient to be on cardiopulmonary bypass for an extended period.
One technique for attaching a prosthetic heart valve to the heart tissue is shown in U.S. Pat. No. 4,705,516 in which an outer orifice ring is sutured to the tissue annulus and an inner orifice ring is then screwed into the outer orifice ring. However, the rings are not locked together and may become unscrewed after extended use.
A prosthetic heart valve for implantation in a heart is provided which includes an outer orifice ring, an attachment mechanism on the outer orifice ring adapted to couple the outer orifice ring to a tissue annulus of the heart, an inner orifice ring having an occluding mechanism carried therein, and a ring coupling mechanism adapted to couple. the outer orifice ring to the inner orifice ring after the outer orifice ring has been coupled to the tissue annulus. The coupling mechanism includes a first helical thread on an outer diameter of the inner ring and a second helical thread on an inner diameter of the outer ring. At least one of the diameters includes a retaining ridge configured to define an unthreaded region between the retaining ridge and the respective thread. When a helical thread is positioned in the unthreaded region, the inner ring is rotatable in the outer ring with substantially no movement in an axial direction of the valve.